This invention relates generally to cement mixing, and more particularly to separating, measuring and mixing an admixture of components for lightweight cement. Recycled lightweight concrete waste materials may hereby be recycled. This method and apparatus is an improvement of the existing process described in my U.S. Pat. No. 4,895,450, incorporated herein by reference.
Lightweight concrete consists mainly of cement, water, and an admixture of lightweight filler, the filler comprising such materials as polystyrene, crushed pumice, and perlite. Lightweight concrete blocks are formed from this cementious mixture by pouring the mixture into block forms, allowing the cement to cure, and cutting the blocks to the desired shape. Waste material is created when the blocks are cut, the waste comprising hydrated cement dust, lightweight filler, and concrete lumps. Because the residual cement has already been hydrated, the waste materials will no longer bind without additional binders. The waste material may be recycled, however, by adding it to a fresh mixture of lightweight cement, which will bind with the waste material.
The prior art process is described in detail in U.S. Pat. No. 4,895,450, hereinafter the '450 patent. That process greatly simplified the measuring of the various ingredients by providing two different chambers into which the ingredients are placed. In a first hopper, filler material contained in hydrated cement and fresh filler material are measured by volume, and the hydrated cement is measured by weight. In a second hopper, water and cement are measured by weight.
Before recycling residual lightweight concrete, it is necessary to separate the components of the waste materials. This involves separating the dust and lightweight filler from the heavier concrete lumps. Furthermore, lightweight filler particles that have adhered to the concrete lumps should be removed. Because the ratios of cement, water, and lightweight filler must be kept within narrow tolerances, all the components must be measured separately. This further complicates the process of making lightweight cement.
Therefore, it is an object of this invention to provide a method and apparatus to use recycled lightweight concrete waste materials to produce lightweight concrete. It is a further object to provide a method and apparatus to separate and measure the waste materials. It is another object of this invention to simplify making lightweight cement blocks by providing a method and apparatus that separates ingredients into a first hopper for weighing materials and a second hopper for volume measuring materials.